I was shocked to not find this route in my Garmin GPS software, as well. The JBR is well covered.
Here is a link to the route on google maps (from the "start" at 167 to the James Bay Road). You can zoom in rather close and follow the whole road and some of the smaller places it passes through (Nemiscau), and lakes it passes by.
http://tinyurl.com/5far78If you're thinking about one week to ride the North Road AND the Trans-Taiga, you might be pushing it. One one hand, I rode from Radisson to North Bay, ON in one day, but that was in good weather on paved roads. Being the TTR is 666km of no pavement, I would think going to the end would take two days by itself. It sounds like it will be a challenging ride, though you have the right bike for it. I'd love to get back up there and ride the TTR. Maybe in the next few years...